Torpedo-steering control and roll-stabilization apparatus

ABSTRACT

Torpedo-steering control and roll-stabilization apparatus comprising four bodily movable steering fins mounted in quadrature relationship around the tail cone with their fin shaft ends extending through the shell wall, and a unitary-actuator assembly for actuating the ends of the fin shafts. The frame of the actuator assembly is an annular ring adapted for transverse mounting across the interior of the shell ahead of the fins. The ring has a substantially square opening with the sides of the opening perpendicular to the fin shaft axes. Three upstanding lugs are affixed to the front face of the ring adjacent three of the sides of the opening. The upstanding lugs carry three identical fin actuators including a servomotor driven worm meshed with a worm wheel. The worm wheel has an aperture along its axis adapted to engage the inner ends of the fin shafts along its axis. The actuators are fastened to the lugs by adjustable means permitting alignment of the worm wheel aperture with the fin shaft prior to the actuator being secured in place. The bodily movable fins have integral fin shafts, with the fin shaft axis passing through the fin slightly ahead of the hydrodynamic center of pressure of the fin. Two diametrically opposite fins are driven independently by different actuators producing a combination joint deflection steering command and a differential deflection steering command to yield steering command and a differential deflection steering command to yield steering control in one steering plane, and yield roll control. The other steering fins are coupled by a yoke and driven by a deflection steering command yielding steering control in the other steering plane.

United States Patent [72] Inventors John D. Brooks San Gabriel; Orrin W.Albert, Jr., Arcadia, both of Calif.

[211 App]. No. 612,305

[22] Filed Jan. 26, 1967 [45] Patented [73] Assignee Sept. 28, 1971 TheUnited States of America as represented by the Secretary of the Navy[54] TORPEDO-STEERING CONTROL AND ROLL- Primary Examiner-Benjamin A.Borchelt Assistant Examiner-Thomas H. Webb Attorneys-G. .l. Rubens, R.Miller, V. C. Muller and M. F.

Oglo

ABSTRACT: Torpedo-steering control and roll-stabilization apparatuscomprising four bodily movable steering fins mounted in quadraturerelationship around the tail cone with their fin shaft ends extendingthrough the shell wall, and a unitary-actuator assembly for actuatingthe ends of the fin shafts. The frame of the actuator assembly is anannular ring adapted for transverse mounting across the interior of theshell ahead of the fins. The ring has a substantially square openingwith the sides of the opening perpendicular to the fin shaft axes. Threeupstanding lugs are affixed to the front face of the ring adjacent threeof the sides of the opening. The upstanding lugs carry three identicalfin actuators including a servornotor driven worm meshed with a wormwheel. The worm wheel has an aperture along its axis adapted to engagethe inner ends of the fin shafts along its axis. The actuators arefastened to the lugs by adjustable means permitting alignment of theworm wheel aperture with the fin shaft prior to the actuator beingsecured in place. The bodily movable fins have integral fin shafts. withthe fin shaft axis passing through the fin slightly ahead of thehydrodynamic center of pressure of the tin. Two diametrically oppositefins are driven independently by different actuators producing acombination joint deflection steering command and a differentialdeflection steering command to yield steering command and a differentialdeflection steering command to yield steering control in one steeringplane, and yield roll control. The other steering fins are coupled by ayoke and driven by a deflection steering command yielding steeringcontrol in the other steering plane.

PATENTED SEP28l97| 3,608,509

SHEET 2 UF 2 INVENTORS. JOHN D. BROOKS MICHAEL P OGLO ROY MILLERATTORNEYS.

ORRIN w. ALBERT,JR.

TORPEDO-STEERING CONTROL AND ROLL- STABILIZATION APPARATUS The inventiondescribed herein may be manufactured and used by or for the Governmentof the United States of America for governmental purposes without thepayment of any royalties thereon or therefor.

The invention relates to torpedo steering surface apparatus of the typein which four quadrature-spaced deflection surfaces are operated toprovide triaxial control, i.e. control in two steering planes and rollcontrol.

From the earliest times, torpedoes have required fixed stabilizationfins to provide roll stability. The principle of providing roll controlby means of a differential deflection command between a pair ofdiametrically opposite steering surfaces has been used to increase rollstability. This has been disclosed in US. Pat. No. 2,974,260 to F. S.Malick et al., entitled Triaxial Control System." However, the apparatusof that patent operated small steering tabs only, and fixed stabilizingfin structure was nevertheless still required to achieve roll stability.

An object of the present invention is to provide steering apparatuswhich achieves triaxial control without the need of any fixedstabilization surface, whatsoever.

Another objective is to provide apparatus in accordance with thepreceding objective which can be made by standard manufacturing methods,and which nevertheless meets the severe environmental and performancerequirements of modern air-dropped, high-speed, antisubmarine torpedoes.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawings wherein:

FIG. I is a central longitudinal section of the tail cone zone of atorpedo, portions being shown in side elevation;

FIG. 2 is a view of the unitary actuator assembly taken along arrow 2,FIG. 1, the torpedo shell, motor and drive shaft being omitted forclarity;

FIG. 3 is a view taken at line 3-3, FIG. 2;

FIG. 4 is an enlarged view of a detail taken at the line 4-4, FIG. 3;

FIG. 5 is a detailed enlarged longitudinal section of the end portionofa fin shaft in FIG. 3; and

FIG. 6 is a section taken along lines 66, FIG. 2.

Referring now to FIG. 1 of the drawing, there is shown a tail portion ofan antisubmarine homing torpedo l0 whereat the propulsion systemelements and steering apparatus are located. A tail cone 12 isconcentrically aligned about the torpedo axis A, and has a removablepropeller shaft block 14 threaded in place at its rear end. A pair ofyaw steering fins l6U and 161. and a pair of pitch steering fins 16S and16? are rotatably mounted to the shell by means of shaft bearings 18associated with inwardly projecting bosses 22 formed on the innersurface of the shell. The yaw steering fins 16U, 16L are aligned about avertical axis B and the pitch steering fins 16S, 16? about a horizontalaxis C, FIG. 2. The fins all have integral shafts 20 so that the entirefin bodily moves under rotation of its shaft. Each fin shaft axis islocated slightly ahead of the center of pressure (indicated on thedrawing as C. P.) of the fin surface. A propulsion motor and associatedoutput gearing is contained in a centrally mounted housing 26 having abell-shaped rear end. A pair of axially aligned concentriccontrarotating drive shafts 28a, 28b, drive a contrarotating propellersystem comprising hub and propeller assemblies 30a, 30b. A unitaryactuator assembly 32 for driving all three fins comprises a ring 34attached by anchor boats to planar surfaces on the front sides of bosses22, and three identical individual actuators 36U, 36L and 36$, fordriving fins 16U, 16L and 168 respectively. The shaft of fin 16P isconnected to the shaft of fin 165 by a clamping block attached to yokeassembly 38, FIG. 2, having a central aperture through which drive shaft28 may extend. A U-shaped bracket 40 for holding a multiconnectionelectric plug 42 is affixed to ring 34. For purposes of simplicity, muchof the wiring between components of the actuator and multiconnectionplug 42 is omitted.

Referring now to FIGS. 2 and 3, ring 34 has a substantially squareopening 43 with its sides perpendicular to the steering fin axes B andC. forwardly projecting upstanding lugs 44U, 44L and 448 are affixed tothe front face of ring 34 adjacent to the sides of opening 43 nearestfins l6U, 16L and 16S, respectively. Each lug is laterally offset fromthe fin axis by a distance D, the offset always being to the right-handside of the axis as the lugs appear in FIG. 2. A threaded aperture 46 isprovided in each lug.

Since the actuator assembles are all alike the following description ofarrangements of components thereof will serve for all. A flat gearbox 48contains a worm 50 meshed with a segmental worm wheel 52. The segmentalworm wheel is pivotally held in the box in perpendicular relationship tothe opposite face plates 54a and 54b of the gearbox. The worm 48 isjournaled between sides of the gearbox in alignment along worm axis E. Agearbox lug 56 is formed as an extension of the faceplate 54b of thegearbox. An elongated slot 58 is formed in the gearbox lug having itsmajor axis F parallel to worm axis E. Each individual actuator 36 isfastened to ring 34 by a bolt 60 which extends outwardly through a slot58 and engages the threaded aperture 46 of the adjacent upstanding lug44 of the ring. Bolt 60 holds the outer surface of lug 56 in engagementwith inner surface of lug 44, which in turn aligns the gearbox inperpendicular relationship to its associated fin axis. A reversibleservomotor 62 is coupled to worm 50 through a shaft extension 64enclosed by a cylindrical housing 66. Servomotor 62 is ahigh-performance direct-current permanent-magnettype motor having aresponse time of less than 15 milliseconds. (Response time is defined asthe time it takes the motor to accelerate to approximately 63 percent ofits terminal speed.) The requirements for steering a modern highspeedantisubmarine homing torpedo typically require 10 servomotor reversalsper second, so that fast responses are needed. High performanceservomotors may be obtained commercially, as for example, from GlobeIndustries of Dayton, Ohio. The diametrically opposite protuberances 68(best shown in FIG. 2) of the servomotor housing contain thepermanent-magnet structures. The protuberances 68 are disposed in achordal relationship to the interior of shell 12, as best shown in FIG.2. The opposite end 70 of the worm shaft projects from the gearbox inorder to provide a connection for a conventional-shaft-position followuppotentiometer, which has been omitted from the drawings for purposes ofsimplicity.

Segmental worm wheel 52 is journaled between the inner and outerwallplates 54a, 54b and connected to the ends of the fin shafts 20 asfollows. A round bearing shoulder 72 is concentrically formed about theaxis G of the worm wheel on each of the opposite faces. A squareaperture 74 extends through the worm wheel and the bearing shouldersalong axis G. The square aperture is for receiving a square shank 75formed on the end of each fin shaft 20 for purposes of engaging the wormwheel. This square shank is shown in the cutaway of the gearbox ofindividual fin actuator 36L. The bearing shoulders 72 are mounted to thewalls 54a, 54b by means of a ball bearing 76 held in an eccentricbearing retainer ring 78. As best shown in FIG. 4, the inner periphery80 of bearing retainer ring is eccentric (exaggerated in drawing)relative to its outer periphery, so that the axis G of the worm gear isheld in eccentric relationship to the outer periphery of retainer ring78. The retainer ring 78 is fastened to the gearbox wall by three screws82 extending through a flange formed on the retainer ring. A set 86 ofthree incrementally spaced holes are provided for each screw 82, so thatthe eccentric retaining ring can be fastened in any of three incrementalangular positions depending upon which hole of the sets is used. Thisarrangement provides adjustability of the mesh between the worm and wormwheel to compensate cumulative eifects of manufacturing tolerances inminimizing backlash. This adjustment is made at the time of assembly ofthe gearbox. In an operational unit like the embodiment on the drawing,

backlash is maintained to values which enable coupling of the mechanicalmotion from servomotor 62 to the fins without any appreciabledegradation of its 15 millisecond response characteristics.

Each gearbox 48 is attached to the lug 44 with the angle between theworm axis E and the torpedo central plane through the associated finaxis approximately equal to the half angle of the tail cone taper. Theoffset distance D of lugs 44 and the axial distance between the finshaft axis and the aperture 46 in lug 44 are so chosen that this angleplaces square aperture 74 of the segmental worm wheel substantially inposition to receive the square shank 24 of the fin shaft. As best shownin FIG. 5 taken in conjunction with FIG. 3, a longitudinal slit 88extends diagonally between the edges of the square shank 75 and anaxially extending tapped hole 90 having a divergent conical portion 92is formed in the end of the fin shaft. After shank 75 is fitted throughaperture 74 in the worm wheel, a tapered shouldered screw 94 is tightlydriven into opening 90. The engagement of the shoulder of screw 94against conical portion 5 2 of the opening expands the split shankwithin aperture 74, eliminating backlash in this coupling The end of theshaft 20 of fin 168 projects a short distance beyond the gearbox. Theshaft of fin 16!, which does not pass through a gearbox, is the samelength as the shaft of fin 168. These two ends are coupled together forjoint rotation by the clamping block attached to yoke assembly 38, whichconsists of mating members 38a and 38b, FIG. 6. When the mating membersare fastened together, they form clamping block portions to engage thesquare ends of the shafts.

As is conventional with antisubmarine homing torpedoes, torpedo 10 maybe delivered to the point of water impact by a rocket propelled missile,or released from an aircraft. The impact of striking the water islessened by use of drag parachutes. Nevertheless, severe torques areapplied to the fin shafts upon water impact, due to the large area ofthe fins. The fins should remain locked in their neutral positionagainst this torque. In the present apparatus, the requirement oflocking the fin in the neutral position is satisfied by a choice of wormparameters which afford resistance to overhauling under the most severewater impact torque conditions. Overhauling" is defined as the conditionwhere application of a torque to a worm wheel causes the worm to rotate.The parameters which determine overhauling characteristics are the leadangle of the worm and the coefficient of friction between the worm andthe worm wheel. The smaller the lead angle the greater the resistance tooverhauling. The higher the coefficient of friction the greater theresistance to overhauling. Highly satisfactory results have beenobtained in an operational unit like that embodied in the drawing with alead angle of the worm of 5 and 43", and use of a dry lubricant having apredetermined coefficient of friction of approximately 0.]. Such a drylubricant may be composited using an epoxy resin base containing amixture of graphite and molybdenum disulfate.

The unitary actuator assembly 32 is installed in tail cone 12 asfollows. With the bolts 60 holding the individual actuators 36 to thering 34 left loose, the ring 34 is bolted to the fin shaft bosses 22.This is done at a stage of assembly before the motor housing 26,propeller shafts 28a, 28b, and end block 14 are in place. The squareaperture 74 of each segmental worm wheel is aligned with the end shank75 of the corresponding fin, and the fin shank then inserted into theaperture. This is done by the mechanic reaching into the torpedo shellthrough the hole at the rear end of shell 12, manually shifting thegearbox 48 in a plane perpendicular to the fin axis to position theaperture of the worm wheel into alignment with the fin shaft. Thegearbox is shiftable in two dimensions in a plane perpendicular to thefin axis. Elongated slot 58 in gearbox lug 56 allows the gearbox to beshifted in the direction of axis F, providing one dimension of movement.Also, since the aperture 74 is located a substantial distance from bolt60, rotation of the gearbox about the axis of bolt 60 results inshifting the aperture 74 is an arc about the bolt 60, providing theother dimension of movement. After the inner ends of the fin shafts 20have been inserted in the worm wheel apertures, the lug bolts 60 aretightened, and the expander screws 94 in the ends of the fin shafts aredriven in tight, The inner ends of shafts 20S and 20? are than connectedby means of the previously described yoke and assembly 38. Thepropulsion system components and the propeller shaft block of the tailcone are then affixed in place, and necessary electrical connectionsmade by plugging in to multiterminal connection 42. It will be apparentthat installation of the fin and the actuators to the tail cone can beperformed without special tools or training, and without the need forany tuning adjustments after the assembly is in place. The featureenabling shifting of the individual actuators into precise alignmentwith axes B and C, enables interchangeability of shells and actuatorassemblies. After assembled to the torpedo shell the apparatus providesrigid mechanical coupling compatible with the high performance of theser vomotors, and compactly fits in frustoconical annular space betweenthe propeller shafts and bell-shaped rear end of housing 26 and theinner wall of shell 12.

The servomotor for individual actuator 36S, which drives the shaft ofpitch steering fin 16S and fin 16? through the yoke, is operated byconventional pitch steering commands from the torpedo autopilot. Incontrast, fins ll6U and 16L are independently driven by separate motors.The separate inputs to these motors are derived from a triaxial controlarrangement which gives steering fins 16U and 16L combined yawand-rollsteering commands, the roll-steering commands being a differentialdeflection of the steering surfaces. An example of a system for derivinga combined yaw-and-roll command steering signals for independentlydriven upper and lower fins is disclosed in tee copending application ofEdward M. Kimura, Ser. No. 548,820, filed May 4, 1966. Stability of thistriaxial control is achieved by providing sufficiently large areas offins 16, in accordance with conventional hydrodynamic theory. Since thefin shifts 20 are located substantially at the center of pressure of thefins, a minimum of torque is needed to cause their deflection. Animportant feature of the present mode of operation of triaxial controlemploying large bodily moveable steering fins is the elimination of anyneed for any fixed stabilizing surfaces on the tail cone, therebysimplifying the fabrication of the tail cone shell. Another beneficialresult is the availability of deflection of the large fin area duringinitial startup of the torpedo when first dropped in the water. At thistime large steering deflections are desired to quickly orient thetorpedo along its programmed course from its random orientation afterwater impact. During homing control phases of the torpedo operation, thesteering adjustments are made by a minimum of steering surfacedeflection because of the large steering control surface provided by thebodily movable fins. The latter is important because it minimizes thedisturbance of the flow to the propellers, and thereby aids in achievingtorpedo stability under high speeds.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

What is claimed is:

1. A unitary torpedo-steering actuator assembly for positioning withinthe tail cone of a torpedo employing a mode of control surfacedeflection for triaxial control of the torpedo in which a first pair ofaxially aligned control surfaces are jointly deflectable for steering ina longitudinal plane transverse to their axis and a second pair ofaxially aligned control surfaces are disposed perpendicular to the firstpair and in the same transverse plane and are individually deflectablefor steering in a longitudinal plane perpendicular to their axis and fortorpedo roll control about the tail cone axis, the wall of the tail conebeing provided with corresponding first and second diametricallyopposite pairs of control surface shaft bearings at a firstpredetermined longitudinal position, said bearings each being forpivotally supporting a control surface with the water with the controlsurfaces in their neutral position and of construction having a tailcone having a smooth exterior surface without fixed external stabilizingfin appendages and g. the individual control surfaces each comprising abodily inner end of its shaft projecting into the interior of the tailcone, said actuator assembly comprising:

a. a frame formed as a ring with a substantially rectangular opening andadapted to be affixed to the tail cone disposed transversely across theinterior thereof at a 5 deflectable steering fin having sufficient finarea to enable second predetermined longitudinal position, the sides ofcontrol of the stability of the torpedo by said mode of torsaidrectangular opening being perpendicular to the con- P Pnder theconditions of absence of fixed trol surface axes, said ring having afirst upstanding lug lier'nal -"lg fin pp dag adjoining one of the sidesof the pair of sides perpendicu- 531d worm bemg of the nonoverhafllmg WPwhere! [at to the i f the fi t pair f 00mm} surfaces and said actuatorassembly construction inherently locks said Second and third upswndinglugs adjoining one and the fins in therr neutral position against waterentry forces other of the sides of the pair of sides perpendicular tothe actmg upon h steermg fin axis of the second pair of controlsurfaces, and assembly In accordance ith claim 1, where n,

b. first, second, and third identical actuators carried by said secondpredetermined loflgltudmai first, Second, and third upstanding lugs forrotating the i5 forward of the first predetermined longitudinal positron'iespectiveadjacem controlsurface Shaft ends and the upstanding lugs proecting forwardly from the c. the shafts of the first pair of controlsurfaces being rigidly gggggiiggg: 22% 22 2 ;3 1:352 :2? $22 g' f i s:def-legion abolln a axis by 3 the lug on the actuaor l r ousingextending throug h the t roug w ic t e torpe opropel er s a ting mayexten d. each actuator comprising a housing having a worm driven 20$5222: 2 22: 3 1? 3 232:2; 1213252252232 3 by a reversible motor andmeshing with a worm wheel, fg J :31 zzggggsz;gzg gg zfizm'i zg z the j.each upstanding lug being offset by a predetermined J i distance to apredetermined side of longitudinal plane of e. each actuator having anassociated means perrnrttmg 25 the associated Steering fin Shaftshifting of Said actuator housing in a plane perqemiicillar k. the axisof the worm of each actuator being inclined to to comiql Shaft. ans andfor Securirig n m a said longitudinal plane by a predetermined angleapproxidesrred position, said associated means comprising a lug matelyequal to the halfincluded angle of the tan cone on the actuator housinghaving an elongated aperture and and a extending thmugh Said apertureand engaging the 1. said worm drive motor of each actuator beingdisposed assoclated on the frame forward of the ring and connected tothe worm through whereby 531d 'f' assembly, may be F the shaft extensionextending through the opening in the ring as a umtry orgamzanon byaffixmg to whereby the assembly structure is disposed in a conical fcone at Seccnd P -l Posmon annular envelope dimension adjacent to theinner wall of lf the Posmon of each actuator housmg the tail cone toprovide a frustoconical void space forthe and of the Shaft ward of thering into which propulsion drive components 2. Apparatus in accordancewith claim 1 further for use with f the torpedo may project a torpedoadapted for aircraft dropped launching into the

1. A unitary torpedo-steering actuator assembly for positioning within the tail cone of a torpedo employing a mode of control surface deflection for triaxial control of the torpedo in which a first pair of axially aligned control surfaces are jointly deflectable for steering in a longitudinal plane transverse to their axis and a second pair of axially aligned control surfaces are disposed perpendicular to the first pair and in the same transverse plane and are individually deflectable for steering in a longitudinal plane perpendicular to their axis and for torpedo roll control about the tail cone axis, the wall of the tail cone being provided with corresponding first and second diametrically opposite pairs of control surface shaft bearings at a first predetermined longitudinal position, said bearings each being for pivotally supporting a control surface with the inner end of its shaft projecting into the interior of the tail cone, said actuator assembly comprising: a. a frame formed as a ring with a substantially rectangular opening and adapted to be affixed to the tail cone disposed transversely across the interior thereof at a second predetermined longitudinal position, the sides of sAid rectangular opening being perpendicular to the control surface axes, said ring having a first upstanding lug adjoining one of the sides of the pair of sides perpendicular to the axis of the first pair of control surfaces and second and third upstanding lugs adjoining one and the other of the sides of the pair of sides perpendicular to the axis of the second pair of control surfaces, and b. first, second, and third identical actuators carried by said first, second, and third upstanding lugs for rotating the respective adjacent control surface shaft ends, c. the shafts of the first pair of control surfaces being rigidly coupled for joint deflection about their axis by a yoke through which the torpedo propeller shafting may extend, d. each actuator comprising a housing having a worm driven by a reversible motor and meshing with a worm wheel, said worm wheel having an aperture for receiving the inner end of the adjacent control surface shaft, e. each actuator having an associated means permitting shifting of said actuator housing in a plane perpendicular to the control surface shaft axis and for securing it in a desired position, said associated means comprising a lug on the actuator housing having an elongated aperture and a screw extending through said aperture and engaging the associated lug on the frame, f. whereby said actuator assembly may be positioned in the tail cone as a unitary organization by affixing the ring to the tail cone at said second predetermined position and adjusting the position of each actuator housing to receive the inner end of the control surface shaft.
 2. Apparatus in accordance with claim 1 further for use with a torpedo adapted for aircraft dropped launching into the water with the control surfaces in their neutral position and of construction having a tail cone having a smooth exterior surface without fixed external stabilizing fin appendages, and g. the individual control surfaces each comprising a bodily deflectable steering fin having sufficient fin area to enable control of the stability of the torpedo by said mode of torpedo control under the conditions of absence of fixed external stabilizing fin appendages, h. said worm being of the nonoverhauling type, whereby said actuator assembly construction inherently locks said fins in their neutral position against water entry forces acting upon the steering fin area.
 3. An assembly in accordance with claim 1, wherein; i. said second predetermined longitudinal position being forward of the first predetermined longitudinal position and the upstanding lugs projecting forwardly from the front face of the ring, the meshed worm and worm wheel of each actuator being disposed rearward of the ring with the lug on the actuator housing extending through the opening in the ring to a position at least partially in juxtaposed relation to the adjacent upstanding lug on the ring, j. each upstanding lug being offset by a predetermined distance to a predetermined side of longitudinal plane of the associated steering fin shaft, k. the axis of the worm of each actuator being inclined to said longitudinal plane by a predetermined angle approximately equal to the half-included angle of the tail cone, and l. said worm drive motor of each actuator being disposed forward of the ring and connected to the worm through shaft extension extending through the opening in the ring whereby the assembly structure is disposed in a conical annular envelope dimension adjacent to the inner wall of the tail cone to provide a frustoconical void space forward of the ring into which propulsion drive components of the torpedo may project. 